A number of conditions give rise to paediatric deformity, for example scoliosis (or curvature of the spine), club foot, post traumatic deformity such as cubitus varus, knock knees, etc.
Early onset scoliosis is currently managed conservatively with the use of localiser casts and braces to delay curve progression until the child is old enough for definitive treatment by instrumentation and fusion of the curve. Where conservative therapy fails, a variety of surgical procedures are used. For example, convex epiphysiodesis, stapling of the convex side of the curve, short segment fusion, and posterior growing rod systems such as the Harrigton rod, ISOLA® growing rods or the Luque trolley system.
The Luque trolley system is described in French published patent application No 2589716 comprises a pair of U-shaped callipers fixed to the spine, one of the callipers sliding within the other so that the spine may grow. One problem with this system is that the vertebrae of the spine may fuse spontaneously as a result of exposing the spine to fit the callipers.
Using the ISOLA® system, rods are inserted in a way that causes fusion of a small segment of spine proximally and distally to give a solid anchor for the rods. The rods do not control the sagital profile adequately and obtain their correction solely by distraction. In order to lengthen the rods to accommodate growth, the patient must be operated on every six months or so. The purpose of the pediatric ISOLA® is to stabilize the deformity. Definitive treatment of the scoliosis usually involves a further operation where vertebrae are fused together. Insertion of posterior growing rods and the final fusion procedure are relatively major surgical procedures especially if a thoracotomy is required for anterior release of the curve prior to insertion of the growing rods.
Factors for the development of early onset scoliosis vary considerably and include idiopathic and neuromuscular aetioligies.
Growth plates are affected by mechanical stimuli. Increased pressure on a growth plate reduces growth rate, whilst decreased pressure on a growth plate or traction can increase growth rate. Once a scoliosis curve develops the biomechanics of the spine are altered resulting in compression of the concave side of the curve and traction on the convex side of the curve. Growth on the concave side of the curve is therefore retarded whilst growth on the convex side is accelerated. The spine grows asymmetrically and the deformity is exacerbated.
In the condition known as “club foot”, treatment aims are to: correct the deformity early, correct the deformity fully, and to hold the correction until growth stops. Two categories of the condition can be identified: those that are easy to correct, where correction is by splintage alone; and those that are resistant to correction, where response to splintage is poor and early operative correction is required.
Where the condition can be corrected by splintage, individual elements of foot rotation are corrected serially. In the Ponsetti method, the complex deformity is corrected by addressing each component in a defined order and only progressing to the next component when the previous has been adequately corrected. It would be useful to have a treatment which addressed all components simultaneously.
Operative correction requires the cutting of tendons and ligaments, which aside from post operative complications, tends to result in the foot being stiff in the long term.
It would therefore be desirable to develop apparatus, the use of which would improve outcomes for sufferers of conditions causing asymmetric growth.